Wellbore fluid treatment in cased wells may be complicated if the well includes multiple perforations along the length of the well. The perforations can access different formations within the well and thus simple injection of treatment fluids would access all formations accessed by all perforations. If the well is horizontal, several perforated sections may be required to access formation rock along the horizontal well. If fluid treatment such as acidizing or hydraulic fracturing is required, then a method of isolating sections within the well may be required. If all perforated sections are open and if treatments are desired in only selected perforations (i.e. selected intervals), other procedures must be employed.
If selected intervals are to be treated (fracturing or acidizing for example) with well treating fluids, it may be desirable to control where these fluids are placed, and in what volumes. One method might be to individually perforate and treat intervals. If multiple intervals are to be treated, all steps would be repeated for each treatment.
As such in wells with multiple perforated intervals, isolated fluid treatments may be conducted by running a treatment string into the well such as one disclosed in applicants previous U.S. Pat. Nos. 6,907,936 or 7,108,067. In such a process, ports of the tubing string are positioned adjacent the perforations and packers on the string are positioned to isolate a selected portion of the well about the perforations. Other methods use fluid diversion to place fluids throughout multiple perforated intervals.
Alternately, wellbore treatments may be conducted while perforating. For example, a process may be employed wherein the well is perforated, if any perforations exist therebelow, access to them is plugged as by use of a bridge plug, and the well is then treated. This process maybe repeated for further perforations uphole from the first, by repeating the treatment steps for each operation. This limits efficiencies.
Herein the terms wellbore liner and casing are used interchangeably. Such terms should be considered to include various types of wellbore liners that may include or have formed therein perforations. Such liners may be termed liner, screen, casing, etc.